Sponge Filters
PPI Comparison
4.25" Replacement for Hydro (sponge only)
6" Replacement for Hydro (sponge only)
Hydro Foam Replacement
Hydro Sponge Filter
Old-time Sponge Filter Style
Replacement Sponge for old-time filters
Old-time Sponge Filter Style
Old-time Spong Filter Lift Tube

Filter - Replacement Foam

Regular price $1.90
Shipping calculated at checkout.

Made from our Pro-Level Reticulated Foam, specifically suited for colonizing nitrifying bacteria at the highest levels.

As you can see from the list below, a 4.25" cube contains a lot more foam than a 4" one - over 20% more!

  • 3" cube filter has a volume of 27 cubic inches
  • 3.25" cube filter has a volume of 34 cubic inches
  • 4" cube filter has a volume of 64 cubic inches
  • 4.25" cube filter has a volume of 77 cubic inches
  • 5" cube filter has a volume of 125 cubic inches